PREFACE. 



Under other circumstances the subject-matter of the present volume would 

 have been much increased; it would doubtless have included ample treatises on the 

 voice and on comparative behavior and voice as indices of species relationship and 

 of the direction of evolution in pigeons. If Professor Whitman's term of life had 

 but been extended by the years necessary merely to write up his own completed 

 work, it is probable that this would have sufficed for the production of important 

 treatises on these two last-named subjects. But the condition in which these two 

 divisions of his studies were left has not permitted an extensive presentation by 

 the hands of others. The manuscripts treating of behavior in pigeons were, how- 

 ever, far nearer to a definite and final form. It is chiefly this material that is here 

 organized and made available to others. 



Though the present volume deals with behavior a topic seemingly quite dis- 

 tinct from the subjects of the previous volumes of this work the reader of the 

 earlier volumes will not fail to find occasional strands of continuity between those 

 and this the last. He will, in some cases, here find orthogenesis applied in the 

 fields of instinct and intelligence and will note here again a limited but possible 

 role for natural selection. He will observe that in pigeon behavior and intelligence, 

 origins again seem to reveal themselves as improvements and modifications rather 

 than as chance-wise saltations. Behavior and voice characteristics are noted 

 though they are rather scantily discussed to blend, as did nearly all of the charac- 

 ters previously treated, and the studies here recorded on the reproductive cycle 

 furnish illuminating data, not elsewhere available, as to the mechanism by which 

 "overwork at reproduction" as shown in the second volume produces "weak- 

 ened germs." Though all of these elements of continuity are present, they are 

 quite subsidiary in importance to the chief purposes of the volume, which are, to 

 elucidate and interpret the behavior of doves and pigeons. 



The completed manuscript, as it comes from the hands of Professor Carr, who 

 has very generously and most conscientiously carried out the work of its prepara- 

 tion, can hardly give an adequate idea of the difficulties of his task. He merits 

 much more than the thanks of all who may profit by this volume. Acknowledg- 

 ments are made to the Open Court, and Ginn & Co. publishers respectively of 

 the Monist and of the Biological Lectures for the privilege of republishing parts 



of two papers. 



OSCAR RIDDLE. 



in 



